1. Field of the Invention
The present invention relates to phosphites, and more particularly, relates to neo-alkyl phosphites, the preparation thereof, and polymer compositions stabilized therein.
2. Description of the Related Art
Organic phosphites are known thermal oxidative stabilizing agents for polymers and other organic materials. Such phosphites however typically suffer from one or more of the following problems resulting from structural deficiencies: (a) they degrade to alcohols which undergo H.sub.2 O (water) generation through beta-elimination of a hydrogen with an --OH group, and it is believed that this H.sub.2 O generation can lead to further degradation of the phosphite; (b) they experience hydrolytic instability upon exposure to moisture which attacks the bond between the oxygen atoms and the phosphorus atom (O--P bonds); and (c) they degrade into alcohol degradation products which have boiling points of less than 250.degree. C. which volatilize out of phosphite stabilized polymeric compositions under normal polymer processing conditions, for example degradation products such as low molecular weight diols such as 1,3 propane diol (BP 213.degree. C.), 2,2 dimethyl-1,3 propane diol (BP 206.degree. C.), 2,2 diethyl-1,3 propane diol (BP 240.degree. C.), and 2 methyl, 2 propyl-1,3 propane diol (BP 234.degree. C.). Finally, in processes for making organic phosphites it is desirable to be able to make the phosphite from a direct reaction between alcohols and PCl.sub.3 but if a beta-hydrogen is present in the alcohol, then undesirable alkylchlorides will most likely form.
Neo-alkyl phosphites derived from a neoglycol with PCl.sub.3 are known, see Dever, et al., U.S. Pat. No. 3,714,302, which is incorporated herein by reference. While these neo-alkyl phosphites have no .beta.-hydrogens, they lack stearic bulk on the .alpha.-carbons which merely have hydrogen radicals thereon, thus rendering the phosphites susceptible to hydrolytic instability, and possibly volatile degradation products.
Accordingly, it would be desirable to provide phosphites which have few beta-hydrogens (preferably no beta-hydrogens) and have stearic bulk on the .alpha.-carbon.